Dense fog caused flight delays of up to 45 minutes at the Salt Lake International Airport on Friday, airport officials said.

Visibility was zero at about 8 a.m., causing air traffic controllers to halt operations for 40-45 minutes until the fog cleared, said Federal Aviation Administration hub manager Edd Woslum.Delays throughout the day resulted, he said.

Several seeding flights were dispatched to clear the air. Seeding planes fly a circle around the airport dropping pellets of dry ice that absorb moisture, clearing the fog and briefly improving visibility.